1. Field of the Invention
The present invention relates to a deep bass sound booster device that reproduces a powerful sound having emphasized bass.
2. Description of the Prior Art
FIG. 7 shows a block diagram of a conventional deep bass sound booster device. Bass boosters 101 and 201, having a gain-frequency relationship as shown in FIG. 8, amplify a predetermined frequency band.
When sound is reproduced with headphones through output terminals HL and HR, a bass-frequency sound is depressed due to structure of the headphones. Therefore, it is necessary to compensate this with a pre-arranged gain-frequency property. When headphones are used, this is achieved by selecting a property of the bass boosters 101 and 201 as shown in FIG. 8 with a microprocessor or the like used in a system having a deep bass sound booster device. When loudspeakers are used, a property shown in FIG. 6 is selected.
When reproducing the sound with loudspeakers, left-channel and right-channel stereo signals that are fed through input terminals INL and INR from a sound source are input to high-pass filters 102 and 202 after passing through the bass boosters 101 and 201 respectively. When reproducing the sound with headphones, the stereo signals are reproduced with left and right headphones that are connected to the output terminals HL and HR respectively without passing through the high-pass filters 101 and 202.
Each of the high-pass filters 102 and 202 has a gain-frequency relationship as shown in FIG. 3 and permits only a frequency component higher than a cutoff frequency fc (e.g. 100 Hz) to pass through when signals are fed from the bass boosters 101 and 201. The signals output from the high-pass filters 102 and 202 are converted into audio sounds with left and right mid- to high-range loudspeakers that are connected to output terminals SL and SR respectively.
An adder 301 outputs signals after adding the left-channel and right-channel stereo signals together that are fed to the input terminals INL and INR respectively from the sound source. A bass booster 302, having a gain-frequency relationship as shown in FIG. 4, amplifies a predetermined frequency band T and attenuates another frequency band in the signals that are fed from the adder 301 before feeding out as a resulting signal. The signal output from the bass booster 302 is then converted into an audio sound with a bass (low-range) loudspeaker that is connected to an output terminal SB.
As described above, when the headphones are used, the gain-frequency relationship between the reproduced sound and the sound source will be such a curve as shown in FIG. 8. When the loudspeakers are used, the gain-frequency relationship will be such a curve as shown in FIG. 5. In either case, it is possible to reproduce a powerful audio sound having emphasized bass.
However, according to the aforementioned conventional deep bass sound booster device, it is necessary to arrange individual bass boosters, for example, the bass boosters 101 and 201 for outputting to headphones and the bass booster 302 for outputting to loudspeakers. As a result, this requirement causes an increase in circuit size and cost.